signal parsing - better input validation

The helper function we use for signal name mapping does not
check for negative numbers nor invalid (too-high) ones. This
can yield unexpected error messages:

   # podman kill -s -1 foo
   ERRO[0000] unknown signal "18446744073709551615"

This PR introduces a small wrapper for it that:

  1) Strips off a leading dash, allowing '-1' or '-HUP'
     as valid inputs; and
  2) Rejects numbers <1 or >64 (SIGRTMAX)

Also adds a test suite checking signal handling as well as
ensuring that invalid signals are rejected by the command line.

Fixes: #4746

Signed-off-by: Ed Santiago <santiago@redhat.com>

3 files changed, 6 insertions, 7 deletions

diff --git a/cmd/podman/kill.go b/cmd/podman/kill.go
index aba2008ca..a10546ea9 100644
--- a/cmd/podman/kill.go
+++ b/cmd/podman/kill.go
@@ -3,7 +3,7 @@ package main
 import (
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/pkg/adapter"
-	"github.com/docker/docker/pkg/signal"
+	"github.com/containers/libpod/pkg/util"
 	"github.com/opentracing/opentracing-go"
 	"github.com/pkg/errors"
 	"github.com/spf13/cobra"
@@ -54,7 +54,7 @@ func killCmd(c *cliconfig.KillValues) error {
 
 	// Check if the signalString provided by the user is valid
 	// Invalid signals will return err
-	killSignal, err := signal.ParseSignal(c.Signal)
+	killSignal, err := util.ParseSignal(c.Signal)
 	if err != nil {
 		return err
 	}
diff --git a/cmd/podman/pod_kill.go b/cmd/podman/pod_kill.go
index 064946f72..9f696073d 100644
--- a/cmd/podman/pod_kill.go
+++ b/cmd/podman/pod_kill.go
@@ -6,7 +6,7 @@ import (
 
 	"github.com/containers/libpod/cmd/podman/cliconfig"
 	"github.com/containers/libpod/pkg/adapter"
-	"github.com/docker/docker/pkg/signal"
+	"github.com/containers/libpod/pkg/util"
 	"github.com/pkg/errors"
 	"github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
@@ -60,7 +60,7 @@ func podKillCmd(c *cliconfig.PodKillValues) error {
 	if c.Signal != "" {
 		// Check if the signalString provided by the user is valid
 		// Invalid signals will return err
-		sysSignal, err := signal.ParseSignal(c.Signal)
+		sysSignal, err := util.ParseSignal(c.Signal)
 		if err != nil {
 			return err
 		}
diff --git a/cmd/podman/shared/create.go b/cmd/podman/shared/create.go
index c1c5db7cb..58cf56eea 100644
--- a/cmd/podman/shared/create.go
+++ b/cmd/podman/shared/create.go
@@ -24,7 +24,6 @@ import (
 	"github.com/containers/libpod/pkg/rootless"
 	cc "github.com/containers/libpod/pkg/spec"
 	"github.com/containers/libpod/pkg/util"
-	"github.com/docker/docker/pkg/signal"
 	"github.com/docker/go-connections/nat"
 	"github.com/docker/go-units"
 	"github.com/opentracing/opentracing-go"
@@ -464,7 +463,7 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 		signalString = c.String("stop-signal")
 	}
 	if signalString != "" {
-		stopSignal, err = signal.ParseSignal(signalString)
+		stopSignal, err = util.ParseSignal(signalString)
 		if err != nil {
 			return nil, err
 		}
@@ -624,7 +623,7 @@ func ParseCreateOpts(ctx context.Context, c *GenericCLIResults, runtime *libpod.
 	}
 	if systemd {
 		if signalString == "" {
-			stopSignal, err = signal.ParseSignal("RTMIN+3")
+			stopSignal, err = util.ParseSignal("RTMIN+3")
 			if err != nil {
 				return nil, errors.Wrapf(err, "error parsing systemd signal")
 			}